Ignition system



April 1935- H. c. DOANE 1,998,710

IGNITION SYSTEM Filed May 31, 1933 2554/ fiaazze Patented Apr. 23, 1935 UNITED STATES PATENT OFFICE Motors Corporation, tion of Delaware Detroit, Micln, a corpora- Application May 31, 1933, Serial No. 673,594

3 Claims.

An engine ignition system constitutes in effect a miniature radio broadcasting station and the electrical discharges occurring during engine operation seriously impair and interfere with clear reception by radio apparatus located nearby. Radio interference can be suppressed or eliminated by the insertion in the ordinary ignition circuit of a small carbon resistor, and it is the object of the present invention to provide an improved arrangement for incorporating a suppressor unit in the conventional ignition system without materially changing the general arrangement and relation of parts.

A further object of the invention is to provide an improved cable connector enclosing and permitting easy replacement of the suppressor unit in the event of breakage, and being adapted for use either as original or as accessory equipment.

With the above and other incidental objects in view, as will more fully appear in the following detailed specification, the invention contemplates in a preferred, but not necessarily the only embodiment thereof, the provision of a hollow insulator housing having a spark plug engaging member mounted at one end for electrical connection with a replaceable suppressor unit within the insulator, together with a terminal element secured on the end of the cable and arranged for detachable engagement with the insulator, to retain the suppressor unit in place and make electrical connection therewith.

A better understanding of the structure involved will be had upon reference to the accompanying drawing, wherein Figure l is a side elevation of a portion of an engine, showing terminal connectors associated with each spark plug. Figure 2 is a sectional view taken on line 2-2 of Figure 1. Figure 3 is a section of the connector parts and is taken'on line 3-3 of Figure 2. Figure 4 shows in section, a slight modification of the structure shown in Figure 3, and Figure 5 is a detailed view of the anchor element for the cable separated from the insulator housing.

In the drawing there is shown an engine I, of the over-head valve type, in which the cylinder head is provided with inner and outer walls 2 and 3, defining a cooling jacket or water space, such walls having alined openings in which is fitted a cylindrical tube or sleeve 4, enclosing the spark plug 5 threaded in the wall 2 to present its sparking points in the engine combustion chamber. The outer terminal 6 of the spark plug is located adjacent the side wall of the cylinder block for connection with an insulated cable or electrical lead wire 1, extending beside the cylinder block within a housing I for connection with the distributor device 0, which forms a part of the engine ignition system and functions in the usual way.

The connector between the cable I and spark 5 plug terminal 6 is of the elbow type and involves a hollow insulator body III of bakelite, rubber or the like, the bore ll of which is shouldered or reduced at one end as at H, and carries screw threads i3 at its opposite end which terminate 10 in a flared mouth It to facilitate the introductionof the cable I therein. A laterally extending tube l5 to receive the spark plug terminal 6 is fitted to the reduced end It of the insulator body and is provided with an aperture alined 15 with the bore i2, and through these alined openings there is projected a hollow attachment rivet l1, having its opposite ends peened over to secure the parts together.

At its inner end, the rivet l1 provides a seat 20 for a stick it, of carbon or other suitable electrical impedance material having the proper conductance for the intended purpose, and which is located within the bore H of the insulator. A mounting screw I9 is provided for projection into 25 the insulated cable 1 in electrical contact with the current conducting wires of the cable. Screw threads corresponding to the threads iii are provided on the head 20 of the mounting screw so that the parts may be detachably connected with 30 the head 20 serving as a closure plug for the bore' of the hollow insulator I0. In order to insure electrical connection between the resistor l8 and the rivet I! at one end and the head 2|) at the opposite end, a small coil spring 2i is preferably 35 inserted between the resistor and head and for convenience may be permanently mounted within a depressed pocket formedin the head. This spring will in addition to maintaining good electrical contact between the parts, serve to prevent 40 stress on the suppressor I8 and eliminate the necessity for extreme accuracy in manufacture. The head 20 may be provided with one or more openings 22 for the engagement of a suitable tool to unthread the same in the event the cable I 45 should be accidentally pulled out of the insulator.

In making an installation, the screw I9 is first projected into the end of the cable 1 and then the insulator l0 with the resistor located within its bore is threaded into the screw head. If at any time the suppressor unit should become damaged it may be easily and quickly replaced by the separation of the insulator from the screw head or closure plug.

In the modification of Figure 4, the insulator body 23 carries on its reduced end 24 one leg 25,01 the elbow terminal receiving tube 26. The parts may be anchored by depressing an annular rib 21 in the sleeve 25 into an annular groove of the reduced portion 24. Suitable insulation 28 either integral with or separate from the molded body 23 may also be provided to cover the sleeve 25. To provide a contact or seat for the suppressor unit 29 enclosed within the bore oi. the insulator 23, the rivet 30 is provided in the wall of the elbow fitting 26. In lieu of the rivet 30, the seat may consist of a suitable screw or an embossment in the fitting. The opposite end of the suppressor 29 may be engaged by a coil spring 3! bearing against the head of an ordinary wood screw 32 press fitted in a threaded collar 33. The collar 33 is threadedly engaged within the bore of the insulator body 23 and thus provides a closure plug and a mounting for the screw, which is adapted for anchorage in the end of the spark plug lead wire.

From the above description it willbe apparent that there is provided a simple and inexpensive device, which may be easily and quickly installed in the ignition system of an engine, which is to be operated in the vicinity of radio apparatus. While the embodiment illustrated has been described in specific detail, it is to be understood that the invention is not limited to the exact details referred to, and that such modifications may be made as'come within the scope of the appended claims.

I claim:

1. For use in an engine ignition system for reducing interference to radio communication, a cable terminal spark plug connector, including an insulator having a bore therethrough reduced at one end and screw threaded at its other end throughout substantially half its length and adapted to receive the end portion 01' a current conducting cable, a screw threaded plug engaging the insulator threads and positioned midway between the opposite ends of the insulator, a spreader pin located wholly within the bore and carried by said plug for insertion into the end portion of the cable, a suppressor between said screw threaded plug and the reduced end of the bore, and a spark plug terminal fitting having an anchor rivet projecting through the reduced bore and seating on the internal shoulder thereof and providing a seat for the suppressor.

2. For use in an engine ignition system for reducing interference to radio communication, a cable terminal spark plug connector, including an elbow fitting providing angularly disposed tubular legs one or which is adapted to receive a spark plug terminal, an insulator having a reduced end portion located within the other leg of said fitting and having a bore provided with a shoulder at the reduced end portion, a rivet projecting through the end of the bore and an alined opening in said fitting and seating at opposite ends on said shoulder and the fitting, a suppressor element receivable through the other end oi the bore and seated on said rivet, a plug threaded into the last mentioned end of bore behind said element and spaced a considerable distance from the end of the insulator, and a cable anchor pin carried by said plug and located wholly within the insulator for projection into the end 0! a cable inserted into the bore.

3. The combination of a resistor; an insulating case receiving the resistor; a rigid post leading from the resistor and secured to the case and extending in a direction at an angle to the case and forming a support therefor, said post having one member of a snap connection adapted to attach the case and connect an included resistor with a spark plug, the major portion of the post being-between the ends of the case; and a connector leading from the opposite end of the resistor.

HARRY C. DOANF 

